A4 Paper Size — 210 × 297 mm and Inches

A4 paper size is 210 × 297 millimeters. In inches, rounded to two decimals, that is 8.27 × 11.69. The millimeter figures are the ISO 216 definition. The inch figures are a conversion at 25.4 millimeters per inch, so they are not a second official size.

Use 210 × 297 mm in any spec, InDesign file, or CSS page size. Use inches when a US printer or a Word template asks for them. Do not round the millimeters. 210.0 × 297.0 is the trim size, not an approximation.

ISO 216 fixes the A series so that each step is half the sheet above it. Markus Kuhn’s summary of that standard lists A4 as 210 × 297 mm (International standard paper sizes). The full series, including sizes this page does not treat as the main answer, is in the Paper Sizes chart.

A4 in millimeters and inches

Unit	Width	Height
Millimeters	210	297
Centimeters	21.0	29.7
Inches (rounded)	8.27	11.69

Portrait is 210 mm on the short side. Landscape is the same sheet turned: 297 × 210 mm. The name stays A4 either way. If a template says “A4 landscape,” swap the numbers. Do not pick a different format.

Points, for layout apps that think in PostScript points (1/72 inch): about 595 × 842 pt. That rounding is why some PDF libraries call A4 595.28 × 841.89 pt. Prefer millimeters when you talk to a printer.

What size is A4 in inches, exactly?

210 ÷ 25.4 = 8.2677…, which rounds to 8.27. 297 ÷ 25.4 = 11.6929…, which rounds to 11.69. If a dialog only accepts one decimal, 8.3 × 11.7 is the usual one-decimal display. It is slightly coarse. A cutter set to 8.3 inches is 210.8 mm, almost a millimeter off the ISO width. For print, type 8.27 and 11.69, or stay in millimeters.

People also search a4 size document and dimension a4. Those are the same question: the trim size of the page, not the size of the margins inside it. Margins are your choice. The paper is not.

A4 and US Letter

US Letter is 8.5 × 11 inches, which is 215.9 × 279.4 mm. A4 is 5.9 mm narrower and 17.6 mm taller.

	Width	Height
A4	210 mm / 8.27 in	297 mm / 11.69 in
US Letter	215.9 mm / 8.5 in	279.4 mm / 11 in

Letter’s height is 11 inches, not 11.69. The 11.69 figure belongs to A4 only.

They do not substitute. A Letter layout printed on A4 clips the sides or leaves a tall empty band, depending on the scale setting. “Fit to page” changes type size and breaks a careful grid. Pick the sheet your reader will actually have. North America is Letter. Most of the rest of the world is A4. Details of the US sheet are in US Letter Size.

A5, A6, and A3 next to A4

Cut an A4 sheet parallel to its short side and you get two A5 sheets. Cut A5 the same way and you get A6. Put two A4 sheets together along the long side and you get A3.

Size	Millimeters	Inches (rounded)	Relation to A4
A3	297 × 420	11.69 × 16.54	Two A4 sheets
A4	210 × 297	8.27 × 11.69	The reference
A5	148 × 210	5.83 × 8.27	Half of A4
A6	105 × 148	4.13 × 5.83	Half of A5, a quarter of A4

A4 vs A5 is a scale choice, not a close call. A5 is a booklet, a flyer, or a notebook. A4 is a document. A5 vs A6 is the next cut: A6 is a postcard or a small booklet signature. Neither replaces A4 in a contract or a school form.

A3 vs A4 matters when a drawing or a poster must stay readable. A3 is the next drawing size up, not a “large A4.” The A3 numbers and the tabloid comparison are in A3 Paper Size.

Where A4 is the right file

Use A4 for letters, reports, forms, and school work outside North America. Use it for a PDF you will email to a mixed audience only if you also offer Letter, or if you know the readers print on A4. A single PDF cannot be both trim sizes without scaling.

Set the page size before you design the margins. A common office margin is 20 mm or more. That is inside the 210 × 297, not added to it. Bleed, when a color runs off the edge, sits outside the trim. Printers often ask for 3 mm of bleed on digital work. Confirm that with the shop. It is not part of the ISO size.

Folders and envelopes follow the folds. An A4 sheet folded once fits a C5 envelope. Folded in thirds it fits a DL envelope. Those pairings are in Envelope Sizes.

FAQ

What size is A4 paper in inches?

8.27 × 11.69 inches, rounded from 210 × 297 mm. The millimeters are the standard. If a form only allows one decimal place, 8.3 × 11.7 is the coarse display, and it is less accurate for cutting.

Is A4 the same as Letter?

No. Letter is 8.5 × 11 inches (215.9 × 279.4 mm). A4 is narrower and taller. See US Letter Size.

What is half of A4?

A5, at 148 × 210 mm (5.83 × 8.27 in). A6, at 105 × 148 mm, is half of A5.

What does 210 × 297 mm mean?

That pair is A4. Both orientations use the same two numbers. Portrait is 210 wide. Landscape is 297 wide.

What to open next

Set the file to 210 × 297 mm before you place a text frame. If the audience prints in the United States, duplicate the file at Letter size instead of scaling this one. The rest of the A series, and the US sizes beside it, are on the Paper Sizes chart. Poster and drawing sheets start at A2 Paper Size and A3 Paper Size.